Initial lookbook implementation

Pinterest-style visual bookmarking app with:
- URL metadata extraction (OG/Twitter meta, oEmbed fallback)
- Image caching in Postgres with 480px thumbnails
- Multi-tag filtering with Ctrl/Cmd for OR mode
- Fuzzy tag suggestions and inline tag editing
- Browser console auth() with first-use password setup
- Brutalist UI with Commit Mono font and Pico CSS
- Light/dark mode via browser preference

vendor/go.uber.org/multierr/error_post_go120.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2017-2023 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+//go:build go1.20
+// +build go1.20
+
+package multierr
+
+// Unwrap returns a list of errors wrapped by this multierr.
+func (merr *multiError) Unwrap() []error {
+	return merr.Errors()
+}
+
+type multipleErrors interface {
+	Unwrap() []error
+}
+
+func extractErrors(err error) []error {
+	if err == nil {
+		return nil
+	}
+
+	// check if the given err is an Unwrapable error that
+	// implements multipleErrors interface.
+	eg, ok := err.(multipleErrors)
+	if !ok {
+		return []error{err}
+	}
+
+	return append(([]error)(nil), eg.Unwrap()...)
+}